The old phones won't work because they cannot connect to modern networks. The hardware of the phone itself is the issue. However, there are still phones that a

The old phones won't work because they cannot connect to modern networks. The hardware of the phone itself is the issue. However, there are still phones that are just for texting and calling, previously these were referred to as feature phones or basic phones. For example, the Orbic Journey or TCL Flip. As far as I know these all run Android now but lack the ability to install apps and have small screens.